Local Variations in Carbohydrates and Matrix Lignin in Mechanically Graded Bamboo Culms

The mechanical performance of bamboo is highly dependent on its structural arrangement and the properties of biomacromolecules within the cell wall. The relationship between carbohydrates topochemistry and gradient micromechanics of multilayered fiber along the diametric direction was visualized by combined microscopic techniques. Along the radius of bamboo culms, the concentration of xylan within the fiber sheath increased, while that of cellulose and lignin decreased gradually. At cellular level, although the consecutive broad layer (Bl) of fiber revealed a relatively uniform cellulose orientation and concentration, the outer Bl with higher lignification level has higher elastic modulus (19.59–20.31 GPa) than that of the inner Bl close to the lumen area (17.07–19.99 GPa). Comparatively, the cell corner displayed the highest lignification level, while its hardness and modulus were lower than that of fiber Bl, indicating the cellulose skeleton is the prerequisite of cell wall mechanics. The obtained cytological information is helpful to understand the origin of the anisotropic mechanical properties of bamboo.

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Mechanical Properties of Secondary Wall and Compound Corner Middle Lamella near the Phenol-Formaldehyde (PF) Adhesive Bond Line Measured by Nanoindentation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.1746 ◽

2011 ◽

Vol 236-238 ◽

pp. 1746-1751 ◽

Cited By ~ 7

Author(s):

Kun Liang ◽

Guan Ben Du ◽

Omid Hosseinaei ◽

Si Qun Wang ◽

Hui Wang

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Secondary Wall ◽

Phenol Formaldehyde ◽

Middle Lamella ◽

Adhesive Bond ◽

Cellular Level ◽

Bond Line ◽

Line Region ◽

Penetration Behavior

To find out the penetration of PF into the wood cell wall and its effects onthe mechanical properties in the cellular level, the elastic modulus and hardness of secondary wall (S2layer) and compound corner middle lamella (CCML) near PF bond line region were determined by nanoindentation. Compare to the reference cell walls (unaffected by PF), PF penetration into the wood tissues showed improved elastic modulus and hardness. And the mechanical properties decreased slowly with the increasing the distance from the bond line, which are attributed to the effects of PF penetration into S2layer and CCML. The reduced elastic modulus variations were from18.8 to 14.4 GPa for S2layer, and from10.1 to 7.65 GPa for CCML. The hardness was from 0.67 to 0.52 GPa for S2layer, and from 0.65 to 0.52 GPa for CCML. In each test viewpoint place, the average hardness of CCML was almost as high as that of S2layer, but the reduced elastic modulus was about 50% less than that of S2layer. But the increase ratio of mechanical properties was close. All the results showed PF penetrates into the CCML. The penetration behavior and penetration depth from bond line were similar in both S2layer and CCML.

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Comparison of mechanical properties of thermally modified wood at growth ring and cell wall level by means of instrumented indentation tests

Holzforschung ◽

10.1515/hf.2009.085 ◽

2009 ◽

Vol 63 (4) ◽

Cited By ~ 21

Author(s):

Stefanie Stanzl-Tschegg ◽

Wilfried Beikircher ◽

Dieter Loidl

Keyword(s):

Mechanical Properties ◽

Cell Wall ◽

Thermal Treatment ◽

Mechanical Performance ◽

Growth Ring ◽

Beech Wood ◽

Thermal Modification ◽

Wood Structure ◽

Instrumented Indentation ◽

Indentation Tests

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

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Anisotropic Mechanical Properties of Rapid Prototyping Parts Fabricated by Stereolithography

Science of Advanced Materials ◽

10.1166/sam.2021.4071 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1812-1819

Author(s):

Na-Na Yang ◽

Hao-Rui Liu ◽

Ning Mi ◽

Qi Zhou ◽

Li-Qun He ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Elastic Modulus ◽

Brittle Fracture ◽

Fracture Surface ◽

Elongation At Break ◽

Build Orientation ◽

Range Distribution ◽

Anisotropic Mechanical Properties ◽

Orientation Experiment

Stereolithography (SLA)-manufactured parts behave with anisotropic properties due to the varying interface orientations generated by the layer-based manufacturing process. Part build orientation is a very important factor of anisotropic mechanical properties. In this paper, the build orientation experiment was designed to study the anisotropic behaviour of the mechanical properties of the SLA parts based on the orientation relationship between the force and the layer. The results show that there are obvious brittle characteristics on the fracture surface of the specimens and microcracks perpendicular to the direction of the layer distributed on the side of the fracture. The mechanical properties under brittle fracture have different degrees of sensitivity to the build orientation. Among all the build orientations, whether a specimen is built flat or on an edge shows obvious difference in tensile strength, and the relative range distribution reaches 35%. The changes in elastic modulus and the elongation at break are the most obvious in different angles relative to the XY plane, and the relative range distribution reaches 62% and 56% respectively. In all the build orientations designed, the tensile strength is the largest when it is placed on the edge at 0° with Y-axis in the XY plane, the elastic modulus is the largest when it was placed vertically, and the elongation at break is the largest when it is placed flat at 45° with Y-axis in the XY plane.

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On the Temperature-Related Mechanical Properties of UV-LIGA Nickel Material

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.645-646.926 ◽

2015 ◽

Vol 645-646 ◽

pp. 926-930 ◽

Cited By ~ 2

Author(s):

Shuang Shi Yuan ◽

Guang He ◽

Ming Zhang ◽

Guo Zhong Li

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Yield Stress ◽

Environmental Temperature ◽

Experimental System ◽

Failure Stress ◽

Uniaxial Tensile ◽

Mechanical Parameters ◽

Static Mechanical ◽

The Relationship

MEMS nickel material is commonly used for structural material in micro devices. In order to study the effect of environmental temperature on its mechanical properties,this paper has built up a experimental system which can measure the temperature-related static mechanical parameters of the UV-LIGA nickel material. By using the system for uniaxial tensile experiments of the micro specimen under different temperature, the stress-strain curves of the micro specimen under different temperature were obtained; the mechanical parameters of the micro specimen such as elastic modulus, yield stress and failure stress under different temperature were also calculated out;Finally, the relationship between temperature and mechanical parameters including elastic modulus, yield stress and failure stress was analyzed.

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Electrospun polyester-urethane scaffold preserves mechanical properties and exhibits strain stiffening during in situ tissue ingrowth and degradation

10.1101/783522 ◽

2019 ◽

Author(s):

Hugo Krynauw ◽

Rodaina Omar ◽

Josepha Koehne ◽

Georges Limbert ◽

Neil H Davies ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Mechanical Performance ◽

Hydrolytic Degradation ◽

Material Strength ◽

Fibre Direction ◽

Tissue Ingrowth ◽

Polyester Urethane

AbstractConsistent mechanical performance from implantation through healing and scaffold degradation is highly desired for tissue-regenerative scaffolds, e.g. when used for vascular grafts. The aim of this study was the paired in vivo mechanical assessment of biostable and fast degrading electrospun polyester-urethane scaffolds to isolate the effects of material degradation and tissue formation after implantation. Biostable and degradable polyester-urethane scaffolds with substantial fibre alignment were manufactured by electrospinning. Scaffold samples were implanted paired in subcutaneous position in rats for 7, 14 and 28 days. Morphology, mechanical properties and tissue ingrowth of the scaffolds were assessed before implantation and after retrieval. Tissue ingrowth after 28 days was 83 ± 10% in the biostable scaffold and 77 ± 4% in the degradable scaffold. For the biostable scaffold, the elastic modulus at 12% strain increased significantly between 7 and 14 days and decreased significantly thereafter in fibre but not in cross-fibre direction. The degradable scaffold exhibited a significant increase in the elastic modulus at 12% strain from 7 to 14 days after which it did not decrease but remained at the same magnitude, both in fibre and in cross-fibre direction. Considering that the degradable scaffold loses its material strength predominantly during the first 14 days of hydrolytic degradation (as observed in our previous in vitro study), the consistency of the elastic modulus of the degradable scaffold after 14 days is an indication that the regenerated tissue construct retains it mechanical properties.

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Mechanical performance of HMA-2 modified with purified and unpurified carbon nanotubes and nanofibers

Ingeniería e Investigación ◽

10.15446/ing.investig.v37n2.58649 ◽

2017 ◽

Vol 37 (2) ◽

pp. 99-106

Author(s):

Mario Rodrigo Rubio ◽

Duván Julián Martínez ◽

Carlos Enrique Daza ◽

Fredy Alberto Reyes

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Elastic Modulus ◽

Mechanical Performance ◽

Resilient Modulus ◽

Type Ii ◽

Dynamic Characterization ◽

Traffic Loads ◽

Nickel Copper

The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2) modified with carbon nanotubes and carbon nanofibers (CNTF). CNTF were made by means the Catalytic Vapor Deposition (CVD) technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl) catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1) HMA-2 modified with purified CNTF; 2) HMA-2 modified with non-purified CNTF and, 3) a Conventional HMA-2 (control). Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr) and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatiguerelated issues and improve the long-term durability of flexible pavements.

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Elastic Mechanical Properties of 45S5-Based Bioactive Glass–Ceramic Scaffolds

Materials ◽

10.3390/ma12193244 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3244 ◽

Cited By ~ 4

Author(s):

Francesco Baino ◽

Elisa Fiume

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Elastic Modulus ◽

Shear Modulus ◽

Glass Ceramic ◽

Poisson’S Ratio ◽

Mechanical Performance ◽

Poisson's Ratio ◽

Shear Moduli ◽

Bioactive Scaffolds

Porosity is recognized to play a key role in dictating the functional properties of bioactive scaffolds, especially the mechanical performance of the material. The mechanical suitability of brittle ceramic and glass scaffolds for bone tissue engineering applications is usually evaluated on the basis of the compressive strength alone, which is relatively easy to assess. This work aims to investigate the porosity dependence of the elastic properties of silicate scaffolds based on the 45S5 composition. Highly porous glass–ceramic foams were fabricated by the sponge replica method and their elastic modulus, shear modulus, and Poisson’s ratio were experimentally determined by the impulse excitation technique; furthermore, the failure strength was quantified by compressive tests. As the total fractional porosity increased from 0.52 to 0.86, the elastic and shear moduli decreased from 16.5 to 1.2 GPa and from 6.5 to 0.43 GPa, respectively; the compressive strength was also found to decrease from 3.4 to 0.58 MPa, whereas the Poisson’s ratio increased from 0.2692 to 0.3953. The porosity dependences of elastic modulus, shear modulus and compressive strength obeys power-law models, whereas the relationship between Poisson’s ratio and porosity can be described by a linear approximation. These relations can be useful to optimize the design and fabrication of porous biomaterials as well as to predict the mechanical properties of the scaffolds.

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Morphology and Material Composition of the Mouthparts of Stromatium unicolor Olivier 1795 (Coleoptera: Cerambycidae) for Bionic Application

Forests ◽

10.3390/f11070715 ◽

2020 ◽

Vol 11 (7) ◽

pp. 715 ◽

Cited By ~ 1

Author(s):

Roberto D. Martínez ◽

Luis-Alfonso Basterra ◽

Luis Acuña ◽

José-Antonio Balmori

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Cutting Tools ◽

Optical Microscope ◽

Composition Analysis ◽

X Ray ◽

Longhorn Beetle ◽

Xylophagous Insects ◽

Molecular Compounds ◽

Microscopic Techniques

Research Highlights: The novelty of this study is the deep analysis of the morphologic, geometric and mechanical performance of longhorn beetle larvae mouthparts. Furthermore, a metal nano identification of jaw reinforced parts was made. Background and Objectives: Analysis of insect mechanical properties has shown an important application in the develop of bionic technologies such as new materials, industrial machines and structural concepts. This study aims to determine the mechanical and geometric properties of longhorn beetle (Stromatium unicolor Olivier 1795) larvae mouthparts to improve the development of innovative cutting tools. In addition, this study obtains a nano identification of metals in the cuticle of the mouthparts, which will enable the development of new nontoxic and sustainable preservation agents against xylophagous insects based on nanoparticles. Materials and Methods: five third-larval-stage samples of Stromatium unicolor were used to study its mandible morphologic, geometric and mechanical properties. To this end, mouthparts were analyzed by several microscopic techniques using a scanning electron microscope, a stereomicroscope and an optical microscope. Composition analysis was performed using with two Analytical-Inca X-ray detectors, dispersive energy spectroscopy and dispersive wavelength spectroscopy. Results: The main geometric parameters of the insect jaw are the edge angle (β = 77.3°), maximum path depth of the insect (120 μm), length (800 µm) and mouthpart movement, which were identified and measured. The chemical analysis results of the jaw tissues shows the presence of zinc and manganese. Conclusions: The geometry and angles of the mouthparts can be applied in the fabrication of bionic self-sharpening cutting tools. Molecular compounds that form the reinforcing elements in the jaws can be used to develop wood preservatives based on nanometals and metal absorption and metabolism inhibitors.

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Robust topological designs for extreme metamaterial micro-structures

Scientific Reports ◽

10.1038/s41598-021-94520-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tanmoy Chatterjee ◽

Souvik Chakraborty ◽

Somdatta Goswami ◽

Sondipon Adhikari ◽

Michael I. Friswell

Keyword(s):

Mechanical Properties ◽

Topology Optimization ◽

Elastic Modulus ◽

Robust Design ◽

Poisson’S Ratio ◽

Mechanical Performance ◽

Poisson's Ratio ◽

Mechanical Metamaterials ◽

Homogenization Approach ◽

Micro Structures

AbstractWe demonstrate that the consideration of material uncertainty can dramatically impact the optimal topological micro-structural configuration of mechanical metamaterials. The robust optimization problem is formulated in such a way that it facilitates the emergence of extreme mechanical properties of metamaterials. The algorithm is based on the bi-directional evolutionary topology optimization and energy-based homogenization approach. To simulate additive manufacturing uncertainty, combinations of spatial variation of the elastic modulus and/or, parametric variation of the Poisson’s ratio at the unit cell level are considered. Computationally parallel Monte Carlo simulations are performed to quantify the effect of input material uncertainty to the mechanical properties of interest. Results are shown for four configurations of extreme mechanical properties: (1) maximum bulk modulus (2) maximum shear modulus (3) minimum negative Poisson’s ratio (auxetic metamaterial) and (4) maximum equivalent elastic modulus. The study illustrates the importance of considering uncertainty for topology optimization of metamaterials with extreme mechanical performance. The results reveal that robust design leads to improvement in terms of (1) optimal mean performance (2) least sensitive design, and (3) elastic properties of the metamaterials compared to the corresponding deterministic design. Many interesting topological patterns have been obtained for guiding the extreme material robust design.

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The Relationship between Mechanical Properties and Shrinkage of the Concretes Used in Florida

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.3799 ◽

2012 ◽

Vol 204-208 ◽

pp. 3799-3804

Author(s):

Yan Jun Liu ◽

Mang Tia

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Elastic Modulus ◽

Empirical Relationship ◽

Lightweight Aggregate ◽

Shrinkage Strain ◽

Coarse Aggregates ◽

Concrete Mixtures ◽

The Relationship ◽

Mineral Additives

This paper investigated the mechanical strength and shrinkage properties of the concrete mixtures frequently used in Florida. The concrete mixtures were proportioned with three different types of coarse aggregates, such as Miami Oolite limestone, Georgia granite and Stalite lightweight aggregate, and two mineral additives, including fly ash and slag. And fourteen concrete mixtures were evaluated on their characteristics of compressive strength, elastic modulus and shrinkage for 91 days. The empirical relationship between the mechanical properties of concretes and shrinkage strain was analyzed mathematically. The results indicate that the compressive strength and elastic modulus of concrete are exponentially related the shrinkage strain of concrete. The finding from this study is agreeable with that by Troxell et al [5]. Also, the effectiveness of ACI 209 and CEB-FIP models on predicting the shrinkage behavior of concretes used frequently in Florida was evaluated. The result indicates that CEB-FIP model gives more reliable prediction than ACI 209 model does.

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